File: jcmainct.c

package info (click to toggle)
libjpeg-turbo 1:1.5.1-2
  • links: PTS, VCS
  • area: main
  • in suites: stretch
  • size: 9,068 kB
  • ctags: 6,369
  • sloc: ansic: 43,407; asm: 25,683; sh: 5,436; java: 3,123; makefile: 797; xml: 24
file content (162 lines) | stat: -rw-r--r-- 5,155 bytes parent folder | download | duplicates (12)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
/*
 * jcmainct.c
 *
 * This file was part of the Independent JPEG Group's software:
 * Copyright (C) 1994-1996, Thomas G. Lane.
 * It was modified by The libjpeg-turbo Project to include only code relevant
 * to libjpeg-turbo.
 * For conditions of distribution and use, see the accompanying README.ijg
 * file.
 *
 * This file contains the main buffer controller for compression.
 * The main buffer lies between the pre-processor and the JPEG
 * compressor proper; it holds downsampled data in the JPEG colorspace.
 */

#define JPEG_INTERNALS
#include "jinclude.h"
#include "jpeglib.h"


/* Private buffer controller object */

typedef struct {
  struct jpeg_c_main_controller pub; /* public fields */

  JDIMENSION cur_iMCU_row;      /* number of current iMCU row */
  JDIMENSION rowgroup_ctr;      /* counts row groups received in iMCU row */
  boolean suspended;            /* remember if we suspended output */
  J_BUF_MODE pass_mode;         /* current operating mode */

  /* If using just a strip buffer, this points to the entire set of buffers
   * (we allocate one for each component).  In the full-image case, this
   * points to the currently accessible strips of the virtual arrays.
   */
  JSAMPARRAY buffer[MAX_COMPONENTS];
} my_main_controller;

typedef my_main_controller *my_main_ptr;


/* Forward declarations */
METHODDEF(void) process_data_simple_main
        (j_compress_ptr cinfo, JSAMPARRAY input_buf, JDIMENSION *in_row_ctr,
         JDIMENSION in_rows_avail);


/*
 * Initialize for a processing pass.
 */

METHODDEF(void)
start_pass_main (j_compress_ptr cinfo, J_BUF_MODE pass_mode)
{
  my_main_ptr main_ptr = (my_main_ptr) cinfo->main;

  /* Do nothing in raw-data mode. */
  if (cinfo->raw_data_in)
    return;

  if (pass_mode != JBUF_PASS_THRU)
    ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);

  main_ptr->cur_iMCU_row = 0;   /* initialize counters */
  main_ptr->rowgroup_ctr = 0;
  main_ptr->suspended = FALSE;
  main_ptr->pass_mode = pass_mode;      /* save mode for use by process_data */
  main_ptr->pub.process_data = process_data_simple_main;
}


/*
 * Process some data.
 * This routine handles the simple pass-through mode,
 * where we have only a strip buffer.
 */

METHODDEF(void)
process_data_simple_main (j_compress_ptr cinfo,
                          JSAMPARRAY input_buf, JDIMENSION *in_row_ctr,
                          JDIMENSION in_rows_avail)
{
  my_main_ptr main_ptr = (my_main_ptr) cinfo->main;

  while (main_ptr->cur_iMCU_row < cinfo->total_iMCU_rows) {
    /* Read input data if we haven't filled the main buffer yet */
    if (main_ptr->rowgroup_ctr < DCTSIZE)
      (*cinfo->prep->pre_process_data) (cinfo,
                                        input_buf, in_row_ctr, in_rows_avail,
                                        main_ptr->buffer, &main_ptr->rowgroup_ctr,
                                        (JDIMENSION) DCTSIZE);

    /* If we don't have a full iMCU row buffered, return to application for
     * more data.  Note that preprocessor will always pad to fill the iMCU row
     * at the bottom of the image.
     */
    if (main_ptr->rowgroup_ctr != DCTSIZE)
      return;

    /* Send the completed row to the compressor */
    if (! (*cinfo->coef->compress_data) (cinfo, main_ptr->buffer)) {
      /* If compressor did not consume the whole row, then we must need to
       * suspend processing and return to the application.  In this situation
       * we pretend we didn't yet consume the last input row; otherwise, if
       * it happened to be the last row of the image, the application would
       * think we were done.
       */
      if (! main_ptr->suspended) {
        (*in_row_ctr)--;
        main_ptr->suspended = TRUE;
      }
      return;
    }
    /* We did finish the row.  Undo our little suspension hack if a previous
     * call suspended; then mark the main buffer empty.
     */
    if (main_ptr->suspended) {
      (*in_row_ctr)++;
      main_ptr->suspended = FALSE;
    }
    main_ptr->rowgroup_ctr = 0;
    main_ptr->cur_iMCU_row++;
  }
}


/*
 * Initialize main buffer controller.
 */

GLOBAL(void)
jinit_c_main_controller (j_compress_ptr cinfo, boolean need_full_buffer)
{
  my_main_ptr main_ptr;
  int ci;
  jpeg_component_info *compptr;

  main_ptr = (my_main_ptr)
    (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
                                sizeof(my_main_controller));
  cinfo->main = (struct jpeg_c_main_controller *) main_ptr;
  main_ptr->pub.start_pass = start_pass_main;

  /* We don't need to create a buffer in raw-data mode. */
  if (cinfo->raw_data_in)
    return;

  /* Create the buffer.  It holds downsampled data, so each component
   * may be of a different size.
   */
  if (need_full_buffer) {
    ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
  } else {
    /* Allocate a strip buffer for each component */
    for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
         ci++, compptr++) {
      main_ptr->buffer[ci] = (*cinfo->mem->alloc_sarray)
        ((j_common_ptr) cinfo, JPOOL_IMAGE,
         compptr->width_in_blocks * DCTSIZE,
         (JDIMENSION) (compptr->v_samp_factor * DCTSIZE));
    }
  }
}